In 2016, an estimated 982,000 US children ages 6 to 12 were core participants in tackle football, according to a Sports and Fitness Industry Association survey conducted on more than 24,000 individuals and households.

The number includes any child, boy or girl, who has participated in tackle football 26 or more times a year, whether it is through football organizations, school or even pickup games, the association said.

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That's a 1.8% dip in participation since 2011 -- between 2012 and 2014, youth participation was shrinking by the tens of thousands each year -- but numbers have started to grow, including a 1.7% increase from 2015 to 2016.

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Millions more kids ages 6 to 12 play basketball, baseball and outdoor soccer, according to the association. But some sports have seen larger drops in participation, it said, including track and field, which decreased by 24.7% since 2011, outdoor soccer by 19%, baseball by 8.9% and basketball by 4%.

The decrease in football participation may have been due to concerns of player concussions, noted Jon Butler, executive director of Pop Warner Football, a youth football and cheerleading organization. Other factors might include children specializing in individual sports or fewer children playing organized youth sports overall, he said.

Pop Warner currently has 88,850 kids ages 6 to 12 enrolled in football and has maintained a total football enrollment of more than 225,000 participants in the past five years, according to the organization.

The stability of football participation rates over recent years shows that "there is a strong foundation of kids who love to play football with their parents' support," said Steve Alic, a spokesman for USA Football.

In a 2015 policy statement, the American Academy of Pediatrics' Council on Sports Medicine and Fitness noted that most youth football injuries are minor, but "incidences of severe injuries, catastrophic injuries, and concussion, however, are higher in football than most other team sports and appear to increase with age."

In its recommendations, the pediatricians' organization said that officials and coaches must enforce rules of the game to ensure safety and that a "culture of tolerance for head first, illegal hits ... has to change." It suggests that participants weigh potential health risks against the recreation benefits of proper tackling.

Delaying the introduction of tackling would probably decrease risk or injury, the statement said, and teams should try to have athletic trainers on the sidelines during games and practices.